Are there two qualitatively different perceptual processing modes, Automatic and Controlled search? This proposal will generate data to answer that question. Automatic Search occurs when there is a consistent stimulus to response mapping; it is characterized by learning in long-term memory and fast, parallel, automatic processing of stimuli. Controlled Search occurs when the stimulus to response mapping is varied from trial to trial; it is a short-term memory and fast, parallel, automatic processing of stimuli. These two processes can explain most scanning, visual search, and reflective attention results. The experiments will determine (1) the effect of categories in Automatic and Controlled Search; (2) the rate at which Automatic Search is learned, and how the rate is affected by the number of search targets, and (3) in automatic search paradigms, the effects of practice on the amount of negative transfer, and the rate of relearning, when there is a reversal of the initially learned stimulus to response mappings. This work is aimed to further our understanding of the very basic processes of human information processing. In addition to explicating search and selective attention the results and the two process theories may have important implications to mental disorders and education.